1. Field of the Invention
The invention relates to a belt strap-clamping device for safety belts in motor vehicles which has a roll-up device with a belt strap which is rolled up on a belt drum, and which can be rolled out against a spring force. The belt from the roll-up device is partially wrapped around a deflection member with an arched surface, hinged around an axis, and arranged after the belt drum. The belt strap works in conjunction with a clamping surface which is fixed in a fitting, such that the deflection member is moved, when an increased force above the normal pulling out of the belt is applied to the belt, with clamping of the belt strap between the clamping surface and the deflection member. At normal pulling out of the belt, the deflection member is held at a distance from the clamping surface by the force of a spring.
2. Description of the Prior Art
A known deflection fitting with a clamping device for safety belts (German Published Non-Prosecuted Application, DE-OS No. 25 40 302) has a deflection element in the form of a two-armed lever hingeably supported in a U-shaped fitting-plate. The deflection element is provided at one lever arm with a round deflection pin with a round deflection surface, while the other lever arm forms a part of the clamping device. The belt strap loops partially around the upper deflection pin and runs between a clamping surface of the lower lever arm and a clamping surface which is fastened at the fitting plate. The deflection element is held in the "free" position with respect to the clamping device by a spring at one of the lever arms. At a sudden increase of the pulling force (tension) at the belt strap, i.e. in the case of a crash, the two-armed lever is moved by the turning moment acting on the lever-like deflection element, whereby the belt strap is clamped and arrested between the clamping surface of the deflection element and the fitting plate. As the tension force is reduced, the deflection element is automatically moved back into the "free" released position by the force of the above-mentioned spring. The described concept is construction-wise costly, and requires an exceptionally stable configuration of the deflection element, and its supports, because when loads are applied, very strong lever forces are acting on the deflection element and the bearings due to the relative long lever arms.
Also, a roll-up device for a safety belt is known (German Published Prosecuted Application, DE-AS No. 14 81 969) in which a belt drum for storing the belt and a clamping device are provided within a housing for the clamping and releasing of the belt at any length of pulled-out belt. A clamping jaw with a circle-segment-shaped profile is hingeably supported in the middle of the housing, and is arranged after the belt drum. The belt strap loops around the circle-segment-shaped profile of the clamping jaw. An additional stationary clamping jaw is provided in the height of the wrap-around surface at the housing. A spring-loaded arresting device is in functional connection with the hingeably supported clamping jaw, by which, after belt withdrawal and quick belt rewinding, for example during a crash, a clamping between the two clamping jaws is effected. The arresting device locks the hingeable clamping jaws, and a further withdrawal of the belt is made impossible. The arresting device forms a stop which holds the hingeable jaw in the release position. The above-mentioned stop can be adjusted manually for different operating positions, for example, a released position for putting on the safety belt. This construction is very costly to manufacture and difficult to use.